The invention relates to shelving for pallets in which the compartments defined by the frame are continuous in side by side relation and on top of one another and adapted to receive at least three pallets in rolling engagement on a plane which is inclined toward the unloading side.
In a known kind of shelving for pallets the pallets can only be stacked per compartment in side by side relation and on a plurality of floors. It is a disadvantage of this kind of shelving that a small useful shelf area requires a relatively large space for passageways for movement of the fork-lift trucks which are used to lift the pallets into the individual compartments.
Therefore so-called continuous shelving for pallets was developed in which the pallets can also be placed one behind the other. Such continuos shelving is loaded from one side and unloaded from the other. This requires alleys at both sides of the shelving. Rollers are provided on the shelves of the compartments at an inclination toward the discharge side so that the pallets placed at the loading side roll toward the unloading side. When a pallet is removed from the unloading side, the last pallets introduced roll toward the discharge end.
This type of shelving is suitable for a plurality of similar goods per pallet or compartment, i.e. the successive pallets arriving and then being removed one after the other at the unloading side should contain approximately the same articles. The deeper the continuous run-through shelving is, the more economical the storage. At one side an alley is needed for the loading fork-lift truck, and at the other side an alley is needed for the fork-lift truck used to remove the pallets.
It is the object of the invention to provide shelving for pallets of the kind defined hereinabove wherein a favorable useful relationship is obtained between the shelving area and the passageway area required for loading and unloading, in other words, that the space requirement for the shelving is reduced.
To meet this object it is provided, in accordance with the invention, that the shelving for pallets as specified comprises at least one pair of rails, in each compartment, which extend at an inclination toward the common loading and unloading side and accomodate two flat pallet carriages of different heights in rolling engagement, the lower of the carriages being adapted to roll completely under the higher carriage.
With this embodiment of the shelving for pallets it is thus possible to load and unload each compartment from one side. When a compartment is empty, the carriages rolling along on the inclined rails will roll forwardly against a stop. Then a pallet can be placed on the higher carriage. The fork-lift truck then lifts another pallet somewhat above the level of the surface of the lower carriage and, as the pallet is moved into the compartment, it urges the higher pallet carriage with its pallet toward the rear. This carriage rolls back. Upon putting down the pallet the high pallet carriage with its pallet abuts against the backside of the front pallet. Now a further pallet can be introduced by first lifting it somewhat above the level of the pair of rails and then pushing it into the compartment whereby the lower pallet carriage with its pallet and hereby also the higher pallet carriage with its pallet are pushed toward the rear. After the front pallet has been placed on the pair of rails, the two rear pallets each resting on a pallet carriage are secured against any rolling movement toward the front because there is sufficient frictional locking engagement between the front pallet and the rails so that the pallet cannot be displaced forwardly by the pallets which are supported on roller carriages. It would also be possible to provide supporting rails or beams at the front next to the pair of rails and to have their top surfaces project somewhat above the level of the rails so that the pallets will be set down on these supports rather than on the guide rails. The guide rails and any possible support rails should be provided at such spacing that the prongs of the fork-lift truck may enter between them so that they can be inserted under the pallets rather than into recesses provided for the same. The principle underlying the invention is applicable also to shelving in which no more than two pallets can be placed behind each other. In this case only one carriage is to be provided.
The span of the shelving and thus the width of the individual compartments will determine whether or not several pairs of rails are provided for several rows of pallets to be placed one beside the other. The pairs of guide rails are mounted on the shelves so as to be sloping toward the passageway from which the pallets are introduced and at which they are removed. It is particularly advantageous to provide shelving assemblies of two shelvings for pallets according to the invention positioned at both sides of a single alley. In this case the single alley is used for loading and unloading both shelvings. In this case both shelvings may be placed with their backs against a wall which may be the outside wall of a building. The advantage of a shelving system in accordance with the invention is particularly great when the shelving has to be loaded and unloaded relatively seldom, in other words where, in general, one fork-lift truck is sufficient for loading and unloading.
Conveniently, each pallet carriage is supported by flanged wheels for rolling motion on a pair of rails. If each pallet carriage rolls on its own pair of rails, double flanged wheels may be especially advantageous.
A particular embodiment of the invention provides a single pair of rails only for the higher and the lower carriages. In this case the higher carriage rolls off the rails by means of narrow flanged wheels having their flanges at the outside of the rails and having their roller or flange extend at most up to the middle of the rail head. The lower carriage, at the same time, rolls off the rails by means of narrow flanged wheels which have their flanges engage the inside of the rails and their roller or flange likewise extend, at most, to the middle of the rail head. The flanged wheels of the lower pallet carriage thus are directed outwardly and those of the higher pallet carriage are directed inwardly. The inside free ground clearance under the higher carriage is a little greater than the external profile of the lower carriage so that the latter can roll completely under the higher carriage.
It is especially with this embodiment that a third very flat pallet carriage can be supported for rolling movement on another pair of rails disposed between the first pair of rails. This third carriage will fit completely under the lower pallet carriage which is designed with a corresponding free ground clearance. With this design it is possible for the depth of the shelf to correspond to the depth of four pallets because a total of three pallets can be placed on their respective carriages behind the front pallet which is set down on the pair of guide rails or a pair of support rails.
A further development of the invention provides for at least one upwardly inclined ramp for the rollers, acting as a sloping brake at or beside the front end of the rails to be arranged for the purpose of preventing hard hitting of the forwardly rolling carriage against the stop provided at the front end. As each front pallet is removed, the carriages roll automatically forwardly on the slightly sloping path until they run up on the inclined ramp and become stopped against the abutment means.
Thus all the embodiments of the invention enable the saving of space for the passageways for loading and unloading since the shelving can be filled from one side with two or three or even four pallets in one row pallets. However, two or three rows of pallets normally cannot be reached by the fork-lift truck. It may be convenient for better organization to give the carriages different paint coats and then red painting of the high carriage may be used to signal that the entire depth of the shelf behind the same is empty.
Displacing the carriages on rollers has an advantage over roller trains in that each carriage and thus each pallet requires no more than four wheels whereas, when using roller trains at least six to eight wide rollers are required per pallet. Furthermore, outside of the shelvings the pallets may be set down anywhere so that stones, steel chips and the like are pressed into the underside because, in general, the pallets are made of wood. With such foreign matter adhering to the underside, the roller trains would be damaged and rolling would become more difficult. When placing the pallets on carriages these difficulties are avoided and, as a consequence, trouble-free operation over long periods of time is guaranteed in particularly simple manner and at a very small gradient only.